Okay, imagine taking all the best shonen cliches and rolling it into one awesome actiony bundle.
The story follows Kazuki Moto, an average highschool student (just like every anime ever) that is drawn into a work of fighting monsters called homunculi by Tokiko Tsumura (very similar to Bleach's first few episodes.) while the plot doesn't sound too original (it isnt very original at all to be honest) it is still an enjoyable story to watch.
The art style is very shonen looking, with it looking quite Bleachy. this is not necessarily a bad thing because they do things on order to set it apart from its hollow fighting big brother. the characters look okay and the homunculi look quite interesting.
The action looks really good, with the typical "super powerful mega move with a really long ass name" attacks prevalent throughout the series.
All in all, i really enjoyed Busou Renkin and i would defiantly recommend it to anybody who is into action anime
P.S the dub sucks balls. watch it subbed